"""
@Time ： 2022/11/7 11:19
@Auth ： 陈杰 200320501042
@E-mail : 1612845322@qq.com
"""
class number():
    __result = 0
    def __Total(self,num):
        for i in range(1, (num + 1)):
            self.__result += i

    def GetResult(self,num):
        self.__Total(num)
        return self.__result


if __name__ == '__main__':
    n = number()
    num = int(input("请输入需要求和的数字："))
    if num == 1:
        print("%d的和是：%d"%(n,num.Getresult(n)))
    elif num == 2:
        print("1 + %d的和是：%d" % (n, num.Getresult(n)))
    elif num == 3:
        print("1 + 2 + %d的和是：%d" % (n, num.Getresult(n)))
    else:
        print("1 + 2 + ... + %d的和：%d" % (num, n.GetResult(num)))